Angular velocity sensor

ABSTRACT

An angular velocity sensor includes: a frame including a pair of first beams extending in a first direction and opposed to each other in a second direction orthogonal to the first direction, a pair of second beams extending in the second direction and opposed to each other in the first direction, and connections between those pairs; a drive unit that vibrates the frame in a first plane, to which the first and second directions belong, in a vibration mode in which when one pair of those pairs move closer to each other, the other move away from each other, and vice versa; a first detector that detects, based on the amount of deformation of the frame in the first plane, an angular velocity around an axis of a third direction orthogonal to the first plane; and a support mechanism including a base portion and joint portions.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Japanese Priority PatentApplication JP 2011-040509 filed in the Japan Patent Office on Feb. 25,2011, the entire content of which is hereby incorporated by reference.

BACKGROUND

The present disclosure relates to an angular velocity sensor to be usedfor shake detection for a video camera, operation detection in a virtualreality apparatus, and direction detection in a car navigation system,for example.

As a consumer angular velocity sensor, a vibration-type gyro sensor iswidely used. The vibration-type gyro sensor vibrates a vibrator at apredetermined frequency in advance and detects a Coriolis force appliedto the vibrator by use of a piezoelectric element or the like, tothereby detect an angular velocity. This gyro sensor is incorporated in,for example, an electronic apparatus such as a video camera, a virtualreality apparatus, or a car navigation system and used as a sensor forshake detection, operation detection, direction detection, or the like.

For detecting a posture change in a space by using the gyro sensor ofthis type, there is known a configuration of arranging gyro sensorsalong two or three axis directions orthogonal to each other. Forexample, Japanese Patent Application Laid-open No. HEI 11-211481(paragraph [0017], FIG. 1) (hereinafter, referred to as PatentDocument 1) discloses a configuration allowing three-dimensional angularvelocity detection by mounting three gyroscope vibrators on a flexiblesubstrate and bending the flexible substrate such that the threevibrators are orthogonal to each other. Similarly, Japanese PatentApplication Laid-open No. 2000-283765 (paragraph [0019], FIG. 8)(hereinafter, referred to as Patent Document 2) discloses athree-dimensional angular velocity sensor including a base on whichthree three-armed tuning fork vibrators are arranged so as to beorthogonal to each other in three axis directions.

SUMMARY

In recent years, with a reduction in size of an electronic apparatus, itis desirable to reduce the size and thickness of electronic componentsto be incorporated in the electronic apparatus. However, in theconfigurations of Patent Documents 1 and 2, one of the three vibratorsis arranged such that its longitudinal direction is oriented to avertical direction (thickness direction), and hence it is difficult toreduce the thickness of the sensor. In addition, it is necessary tosuppress a reduction in detection property of an angular velocity due tothe reduction in size.

In view of the above-mentioned circumstances, there is a need to providean angular velocity sensor capable of suppressing a reduction indetection property while achieving a reduction in thickness thereof.

According to an embodiment of the present disclosure, there is providedan angular velocity sensor including an annular frame, a drive unit, afirst detector, and a support mechanism.

The frame includes a pair of first beams, a pair of second beams, and aplurality of connections. The pair of first beams extend in a firstdirection and are opposed to each other in a second direction orthogonalto the first direction. The pair of second beams extend in the seconddirection and are opposed to each other in the first direction. Theplurality of connections connect between the pair of first beams and thepair of second beams.

The drive unit vibrates the frame in a first plane, to which the firstdirection and the second direction belong, in a vibration mode in whichwhen one pair of the pair of first beams and the pair of second beamsmove closer to each other, the other pair move away from each other, andwhen the one pair move away from each other, the other pair move closerto each other.

The first detector detects, based on the amount of deformation of theframe in the first plane, an angular velocity around an axis of a thirddirection orthogonal to the first plane, the frame vibrating in thevibration mode.

The support mechanism includes an annular base portion including aninner peripheral portion surrounding an outside of the frame and aplurality of joint portions that join between the inner peripheralportion and the plurality of connections.

According to the angular velocity sensor, it is possible to detect theangular velocity around the axis of the third direction, based ondeformation of the frame vibrating in the plane orthogonal to the thirddirection. With this, it is possible to detect an angular velocityaround the axis in a thickness direction without increasing a thicknessdimension of the sensor, and hence it is possible to achieve a reductionin thickness of the sensor. Further, the plurality of joint portions canbe deformed following the vibration of the frame, and hence transmissionof vibration between the frame and the base portion is suppressed. Withthis, for example, it is possible to prevent the detection sensibilityof the angular velocity due to disturbance and the like from beingfluctuated and to suppress the detection property from being lowered.

As described above, according to the present disclosure, it is possibleto suppress a reduction in detection property while achieving areduction in thickness of the sensor.

These and other objects, features and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view showing an angular velocity sensor according to afirst embodiment of the present disclosure;

FIG. 2 is a plan view of main parts of the angular velocity sensor;

FIG. 3A shows changes over time of basic vibration of a frame of theangular velocity sensor and FIG. 3B shows changes over time of drivesignals;

FIG. 4A is a plan view schematically showing a state of deformation ofthe frame at a certain point of time, on which an angular velocityaround the Z-axis acts and FIG. 4B is a view showing directions ofCoriolis forces acting on pendulums and respective portions of the framein FIG. 4A;

FIG. 5A is a schematic perspective view for illustrating vibrationstates of the respective pendulums when an angular velocity around theX-axis acts on the frame and FIG. 5B is a schematic perspective view forillustrating vibration states of the respective pendulums when anangular velocity around the Y-axis acts on the frame;

FIG. 6 is a block diagram showing a drive circuit of the angularvelocity sensor;

FIG. 7 are plan views for comparing the size of the angular velocitysensor with the size of an angular velocity sensor according to anotherembodiment of the present disclosure;

FIG. 8 shows one result of experimentation in which the vibrationproperties of two angular velocity sensors having differentconfigurations are evaluated;

FIG. 9 is a plan view showing an angular velocity sensor according to asecond embodiment of the present disclosure;

FIG. 10 is a plan view showing an angular velocity sensor according to athird embodiment of the present disclosure;

FIG. 11 is a plan view of main parts, which shows a modified example ofthe angular velocity sensor; and

FIG. 12 is a plan view of main parts, which shows another modifiedexample of the angular velocity sensor.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to the drawings.

First Embodiment Entire Configuration of Angular Velocity Sensor

FIG. 1 is a plan view showing an entire configuration of an angularvelocity sensor according to a first embodiment of the presentdisclosure. The angular velocity sensor 1 has a longitudinal directionin an X-axis direction, a lateral direction in a Y-axis direction, and athickness direction in a Z-axis direction.

The angular velocity sensor 1 includes a frame 10, pendulums 20, driveunits 30, a first detector 50, a second detector 70, and a supportmechanism 80. The frame 10 is formed to have a substantially rectangularframe-like shape and the pendulums 20 are fixed at its four corners. Thedrive units 30 are constituted of piezoelectric elements provided on atop surface of the frame 10 and vibrate the frame 10 in a predeterminedvibration mode. The first detector 50 electrically detects deformationof the frame 10 in an XY-plane and outputs a detection signalcorresponding to the amount of deformation. The second detector 70electrically detects deformations, in a direction perpendicular to theXY-plane, of the pendulums 20 and outputs detection signalscorresponding to the amounts of deformation. The support mechanism 80supports the frame 10 without prohibiting the vibration mode and ismounted on a fixing portion such as a wiring substrate.

Next, each portion of the angular velocity sensor will be described indetail.

FIG. 2 is a plan view showing a basic configuration of a drive sectionof the angular velocity sensor 1. FIG. 2 shows a configuration exampleof the frame 10, the pendulums 20, the drive units 30, the firstdetector 50, and the second detector 70 of the angular velocity sensor1. In the following, the basic configuration of the drive section ofthis angular velocity sensor will be described with reference to FIG. 2.

[Frame]

Sides of the frame 10 function as vibrating beams and include a pair offirst beams 11 a and 11 b and a pair of second beams 12 a and 12 b. InFIG. 2, the first beams 11 a and 11 b extend parallel to each other inthe Y-axis direction and are constituted of a pair of sides opposed toeach other in the X-axis direction. The second beams 12 a and 12 bextend parallel to each other in the X-axis direction and areconstituted of the other pair of sides opposed to each other in theY-axis direction. The beams 11 a, 11 b, 12 a, and 12 b have the samelength, width, and thickness and the outer appearance of the frame 10has a hollow, substantially square shape.

The frame 10 is formed by subjecting a silicon single crystal substrateto a micro-machining technique. For example, the frame 10 can be formedby using a well-known MEMS (Micro-Electro-Mechanical Systems)manufacturing process. The size of the frame 10 is not particularlylimited. For example, the length of one side of the frame 10 ranges from1000 to 4000 μm, the thickness of the frame 10 ranges from 10 to 200 μm,and the width of each of the beams 11 a, 11 b, 12 a, and 12 b rangesfrom 50 to 200 μm.

In portions corresponding to the four corners of the frame 10, aplurality of connections 13 a, 13 b, 13 c, and 13 d that connect betweenthe first beams 11 a and 11 b and the second beams 12 a and 12 b areformed. Both ends of the first beams 11 a and 11 b and the second beams12 a and 12 b are supported by the connections 13 a to 13 d. As will bedescribed later, the beams 11 a, 11 b, 12 a, and 12 b function as thevibrating beams whose both sides are supported by the connections 13 ato 13 d. The four corners of the frame 10 are not limited to anangulated shape as shown in the drawing. The four corners of the frame10 may be chamfered or may be rounded.

The connections 13 a to 13 d are arranged at the four corners of theframe 10, the four corners corresponding to corners of the square. Inthis embodiment, each of the first beams 11 a and 11 b and the secondbeams 12 a and 12 b is curved and formed in a bow shape as a whole,projecting to the inward side of a square S including the connections 13a to 13 d as the corners.

In other words, the first beams 11 a and 11 b include curved portions 11p and inclined portions 11 v. The curved portions 11 p form recessportions 11 t on an outer peripheral side by projecting to a direction(X-axis direction) in which the curved portions 11 p are opposed to eachother. The inclined portions 11 v fix the both ends of the curvedportions 11 p to the connections 13 a to 13 d. Similarly, the secondbeams 12 a and 12 b include curved portions 12 p and inclined portions12 v. The curved portions 12 p form recess portions 12 t on an outerperipheral side by projecting to a direction (Y-axis direction) in whichthe curved portions 12 p are opposed to each other. The inclinedportions 12 v fix the both ends of the curved portions 12 p to theconnections 13 a to 13 d. The inclined portions 11 v and 12 v supportthe curved portions 11 p and 12 p such that the curved portions 11 p and12 p are positioned in the inward side of the square S.

[Pendulum]

The angular velocity sensor 1 includes first pendulums 21 a and 21 b andsecond pendulums 22 a and 22 b.

The first pendulums 21 a and 21 b are formed in one pair of theconnections 13 a and 13 c (first connections) in a diagonalrelationship. The first pendulums 21 a and 21 b extend in the inside ofthe frame 10 along the diagonal direction. One end of each of the firstpendulums 21 a and 21 b is fixed to the connection portion 13 a or 13 cand the other ends of the first pendulums 21 a and 21 b are opposed toeach other near the center of the frame 10.

The second pendulums 22 a and 22 b are formed in the other pair of theconnections 13 d and 13 b (second connections) in a diagonalrelationship. The second pendulums 22 a and 22 b extend in the inside ofthe frame 10 along the diagonal direction. One end of each of the secondpendulums 22 a and 22 b is fixed to the connection portion 13 d or 13 band the other ends of the second pendulums 22 a and 22 b are opposed toeach other near the center of the frame 10.

The pendulums 21 a, 21 b, 22 a, and 22 b typically have the same shapeand size and are formed at the same time when the outer shape of theframe 10 is machined. The shape and size of the pendulums 21 a, 21 b, 22a, and 22 b are not particularly limited and the pendulums 21 a, 21 b,22 a, and 22 b do not need to have an identical shape. In thisembodiment, the pendulums 21 a, 21 b, 22 a, and 22 b include headportions H formed on a free end side and arm portions L that connectbetween the head portion H and the connections 13 a to 13 d. The armportions L are excited in the XY-plane due to vibration of the beams 11a, 11 b, 12 a, and 12 b as will be described later. The head portions Hfunction as vibrating weights for the beams 11 a, 11 b, 12 a, and 12 b.It should be noted that formation of the pendulums 21 a, 21 b, 22 a, and22 b may be omitted.

The shape of the frame 10 is not limited to the substantially squareshape as described above and may be other quadrangular shapes includinga rectangular shape and a parallelogram shape or may be a substantiallyquadrangular shape equivalent to this. Further, the shape of the frame10 is not limited to the quadrangular shape and may be othermulti-angular shapes including an octagon shape and the like. The beamswhose both ends are supported by the connection portions in the fourcorners may have a linear shape.

[Drive Unit]

The angular velocity sensor 1 includes piezoelectric drive layers as thedrive units 30 that vibrate the frame 10. The piezoelectric drive layersinclude first drive electrodes 301 and second drive electrodes 302.Those drive electrodes 301 and 302 are mechanically deformed dependingon an input voltage and then, a driving force due to the deformationvibrates the beams 11 a, 11 b, 12 a, and 12 b. A deformation directionis controlled according to the polarity of the input voltage.

The first drive electrodes 301 and the second drive electrodes 302 arelinearly formed in top surfaces of the beams 11 a, 11 b, 12 a, and 12 b.More specifically, each of the first drive electrodes 301 and each ofthe second drive electrodes 302 are formed in positions symmetric withrespect to an axis of its beam. In FIG. 1, for the sake of easyunderstanding, the first drive electrodes 301 and the second driveelectrodes 302 are shown by different hatchings. In the example shown inthe drawing, the first drive electrodes 301 are arranged on an inneredge side of the first beams 11 a and 11 b and on an outer edge side ofthe second beam 12 b. The second drive electrodes 302 are arranged on anouter edge side of the first beam 11 a and on an inner edge side of thesecond beams 12 a and 12 b.

The first drive electrodes 301 and the second drive electrodes 302 havethe same configuration. The first drive electrodes 301 and the seconddrive electrodes 302 typically have a stacking structure of a lowerelectrode layer, a piezoelectric material layer, and an upper electrodelayer. The first drive electrodes 301 and the second drive electrodes302 are formed to each have a thickness of from 0.5 to 3 μm, forexample. It should be noted that the frame including the beams on whichthe drive electrodes are to be formed is made of a silicon singlecrystal substrate and on the surfaces on which the drive electrodes areto be formed, insulation films such as silicon oxide films are formed inadvance.

The piezoelectric material layer is polarized and oriented so as toexpand and contract depending on a potential difference between thelower electrode layer and the upper electrode layer. Thus, the lowerelectrode layer of each of the drive electrodes 301 and 302 is connectedto the common reference voltage and to the upper electrode layer of eachof the drive electrodes 301 and 302, an alternating-current voltage inopposite phase is applied, with the result that the first driveelectrodes 301 and the second drive electrodes 302 expand and contractin opposite phase to each other.

The constituent materials of the lower electrode layer, thepiezoelectric material layer, and the upper electrode layer are notparticularly limited. For example, the lower electrode layer isconstituted of stacked films of titan (Ti) and platinum (Pt), thepiezoelectric material layer is constituted of a lead zirconate titanate(PZT), and the upper electrode layer is constituted of platinum. Thoselayers can be formed by using a thin film manufacturing technique suchas a sputtering method, a vacuum evaporation method, or a CVD method.Further, for patterning the formed films, etching using aphotolithography technique can be used.

The first drive electrodes 301 and the second drive electrodes 302 maybe formed in all of the beams 11 a, 11 b, 12 a, and 12 b. Either one ofthe first drive electrode 301 and the second drive electrode 302 may beformed in each beam. Further, when one beam of the pair of beams opposedto each other vibrates, the vibration is transmitted via the connectionsof the frame to the other beam, and thus vibration of the other beam canbe excited. Therefore, the drive electrode may be arranged only in onebeam of the pair of beams opposed to each other.

To the first drive electrode 301 and the second drive electrode 302,voltages in opposite phases are applied such that one expands and theother contracts. With this, the pair of the first beams 11 a and 11 bare bent and deformed in the X-axis direction with their both ends beingsupported by the connections 13 a to 13 d and alternately vibrate in adirection in which they move away from each other and in a direction inwhich they move closer to each other in the XY-plane. Similarly, thepair of the second beams 12 a and 12 b are bent and deformed in theY-axis direction with their both ends being supported by the connections13 a to 13 d and alternately vibrate in a direction in which they moveaway from each other and in a direction in which they move closer toeach other in the XY-plane.

Here, in the pair of the first beams 11 a and 11 b and the pair of thesecond beams 12 a and 12 b, a positional relation between each of thefirst drive electrodes 301 and each of the second drive electrodes 302arranged on the inner edge side and the outer edge side is opposite.Thus, in the case where (center portions of the opposed beams of) thepair of the first beams 11 a and 11 b vibrate in the direction in whichthey move closer to each other, (center portions of the opposed beamsof) the pair of the second beams 12 a and 12 b vibrate in the directionin which they move away from each other. In contrast, in the case wherethe pair of the first beams 11 a and 11 b vibrate in the direction inwhich they move away from each other, the pair of the second beams 12 aand 12 b vibrate in the direction in which they move closer to eachother. At this time, the center portions of the beams 11 a, 11 b, 12 a,and 12 b each form a loop of vibration and their end portions(connections 13 a to 13 d) form nodes of vibration. Hereinafter, such avibration mode is referred to as basic vibration of the frame 10.

The beams 11 a, 11 b, 12 a, and 12 b are driven at their resonantfrequency. The resonant frequency of the beams 11 a, 11 b, 12 a, and 12b is defined depending on their shape, length, and the like. As theresonant frequency in the basic vibration of the frame 10 becomes closerto the resonant frequency in angular velocity detection, the detectionoutput can be increased. In the case where an angular velocity around aZ-axis is detected, those two resonant frequencies hardly depend on thethickness of the frame 10, and hence by reducing the thickness of theframe 10, mechanical displacement due to piezoelectric driving can beincreased. However, if the frame 10 becomes thin, the mechanicalstrength of the frame 10 is lowered, and hence the thickness is set sothat the reliability as a device can be ensured.

Further, as the operating frequency of the vibrating beams becomeslower, the amplitude of the vibrator is increased, and hence for theangular velocity sensor, high property can be obtained. On the otherhand, as the vibrating beams become smaller, the operating frequencytherefor tends to be increased. In this embodiment, the resonantfrequency of the beams 11 a, 11 b, 12 a, and 12 b is set to range from 1to 100 kHz.

FIG. 3A shows changes over time of the basic vibration of the frame 10and FIG. 3B shows changes over time of drive signals 1 and 2. In FIG.3B, a “drive signal 1” corresponds to an input voltage applied to thefirst drive electrode 301 and a “drive signal 2” corresponds to an inputvoltage applied to the second drive electrode 302. As shown in FIG. 3B,the drive signal 1 and the drive signal 2 have alternating-currentwaveforms alternately changing to the opposite phase. With this, theframe 10 changes in an order of (a), (b), (c), (d), (a), and so on inFIG. 3A. The frame 10 vibrates in the vibration mode in which, out ofthe pair of the first beams 11 a and 11 b and the pair of the secondbeams 12 a and 12 b, when one pair move closer to each other, the otherpair move away from each other, and when the one pair move away fromeach other, the other pair move closer to each other.

It should be noted that there is, in effect, a delayed period of timedue to influences of the response period of time, input operatingfrequency, frame resonant frequency of a piezoelectric member after aninput signal is applied until the frame changes (is displaced). In thisexample, assuming that the delayed period of time is sufficiently short,the changes over time of FIGS. 3A and 3B are described.

With the basic vibration of the frame 10 as described above, the firstpendulums 21 a and 21 b and the second pendulums 22 a and 22 b vibratein the XY-plane in synchronism with the vibration of the frame 10 witheach of the connections 13 a to 13 d being the center. The vibration ofthe pendulums 21 a, 21 b, 22 a, and 22 b is excited by the vibration ofthe beams 11 a, 11 b, 12 a, and 12 b. In this case, the first pendulums21 a and 21 b and the second pendulums 22 a and 22 b vibrate (swing) inopposite phase to each other in left- and right-hand swing directionsfrom pivots of the pendulums in the XY-plane, that is, the connections13 a to 13 d.

As shown in FIG. 3A, when the pair of the first beams 11 a and 11 bvibrate in the direction in which they move closer to each other, thefirst pendulum 21 a and the second pendulum 22 a vibrate in thedirection in which they move away from each other (State (b)), and whenthe pair of the first beams 11 a and 11 b vibrate in the direction inwhich they move away from each other, the first pendulum 21 a and thesecond pendulum 22 a vibrate in the direction in which they move closerto each other (State (d)). The first pendulum 21 b and the secondpendulum 22 b also alternately vibrate in the direction in which theymove away from each other and in the direction in which they move closerto each other depending on the vibration direction of the pair of thesecond beams 12 a and 12 b. As described above, the first pendulums 21 aand 21 b and the second pendulums 22 a and 22 b vibrate in oppositephase to each other in synchronism with the basic vibration of the frame10.

In the angular velocity sensor 1 according to this embodiment configuredas described above, when alternating-current voltages in opposite phasesare applied to the drive electrodes 301 and 302, the beams 11 a, 11 b,12 a, and 12 b of the frame 10 vibrate in the vibration mode shown inFIG. 3A. When an angular velocity around the Z-axis acts on the frame 10continuing such basic vibration, a Coriolis force due to the angularvelocity acts on each point of the frame 10, and thus, the frame 10 isdeformed straining in the XY-plane as shown in FIG. 4A. Thus, bydetecting the amount of deformation of the frame 10 in the XY-plane, themagnitude and direction of the angular velocity acting on the frame 10can be detected.

FIG. 4A is a plan view schematically showing a state of deformation ofthe frame 10 at a certain point of time, on which the angular velocityaround the Z-axis acts. FIG. 4B is a view showing directions of Coriolisforces acting on the pendulums and respective portions of the frame inFIG. 4A. It should be noted that for the sake of easy understanding, theshape and state of deformation of the frame 10 are shown slightlyexaggerated.

When an angular velocity around a clockwise direction with the Z-axisbeing the center acts on the frame 10 performing the basic vibration, inrespective points (beams 11 a, 11 b, 12 a, and 12 b and pendulums 21 a,21 b, 22 a, and 22 b) in the frame 10, Coriolis forces proportional tothe magnitude of the angular velocity are generated, in the XY-planeorthogonal to the Z-axis, to directions forming 90 degrees in theclockwise direction with respect to movement directions (vibrationdirections) of the respective points at the point of time. In otherwords, the orientations of the Coriolis forces depend on the directionsof vibration in the points at the point of time, on which the Coriolisforces act as shown in FIG. 4B. With this, the frame 10 is squashed(strained) in the XY-plane, changing from the square shape to asubstantially parallelogram shape.

Here, FIGS. 4A and 4B show a state when a predetermined angular velocityacts about the Z-axis in the clockwise direction. It should be notedthat in the case where the orientation of the angular velocity isreversed (counterclockwise direction), the orientation of the Coriolisforce acting on each point is also reversed.

[First Detector]

The angular velocity sensor 1 includes the first detector 50 thatdetects deformation in the XY-plane due to vibration of the frame 10.The first detector 50 includes a first detection electrode 51 a and asecond detection electrode 51 b.

The first detection electrode 51 a and the second detection electrode 51b are arranged, on an outer edge side of the first beam 11 b, inpositions symmetric with respect to a center portion in its axisdirection. The first detection electrode 51 a and the second detectionelectrode 51 b have the same configuration as those of the driveelectrodes 301 and 302. Each of the first detection electrode 51 a andthe second detection electrode 51 b is constituted of a multilayer bodyof a lower electrode layer, a piezoelectric material layer, and an upperelectrode layer and has a function of converting mechanical deformationof the beam 11 b to an electrical signal.

As shown in FIG. 4A, when an angular velocity is generated around theZ-axis, the beams 11 a, 11 b, 12 a, and 12 b are strained and deformeddue to Coriolis forces in the XY-plane. This straining and deformationoccurs with respect to the beams 11 a, 11 b, 12 a, and 12 b at the sametime. Thus, by providing one of the beams with the detection electrodes51 a and 51 b, it becomes possible to detect an angular velocity actingon the frame 10.

Further, the detection electrodes 51 a and 51 b detect not onlydeformation of the frame 10 due to the angular velocity, but alsodeformation of the beam 11 b in the basic vibration. Here, thedeformation of the frame 10, which is associated with generation of theangular velocity, is symmetric with respect to the center portion in theaxis direction of each beam. In other words, with the center portion ofthe beam 11 b being a boundary, one area is deformed to have aprojecting shape to the inward side of the frame 10 and the other areais deformed to have a projecting shape to the outward side of the frame10. Therefore, an outer edge side in the one area of the beam 11 bcontracts and an outer edge side in the other area expands. The firstdetection electrode 51 a and the second detection electrode 51 b thatare arranged on the outer edge side in those areas output detectionsignals in opposite phases. Thus, by generating a differential signal ofthose detection signals, it becomes possible to remove a basic vibrationcomponent of the beam 11 b and to detect an angular velocity componentwith high accuracy.

[Reference Electrode]

The angular velocity sensor 1 according to this embodiment includes areference electrode 60. The reference electrode 60 is arranged on anouter edge side of the second beam 12 a, parallel to the drive electrode302. The reference electrode 60 has the same configuration as those ofthe drive electrodes 301 and 302. The reference electrode 60 isconstituted of a multilayer body of a lower electrode layer, apiezoelectric detection layer, an upper electrode layer and has afunction of converting mechanical deformation of the beam 12 a to anelectrical signal.

The reference electrode 60 is arranged on the outer edge side of thebeam 12 a and detects vibration of the beam 12 a, which is excited bythe drive electrode 302. The detection output is used to generate areference signal for oscillating the frame 10 in the basic vibration. Itshould be noted that instead of forming the reference electrode 60, asum signal of outputs from the first detection electrode 51 a and thesecond detection electrode 51 b may be generated and the sum signal maybe used as the reference signal.

[Second Detector]

The second detector 70 is constituted of four detection electrodes 71 a,71 b, 72 a, and 72 b. The detection electrodes 71 a, 71 b, 72 a, and 72b are arranged on the top surfaces of the arm portions L of thependulums 21 a, 21 b, 22 a, and 22 b, respectively. Each of thedetection electrodes 71 a, 71 b, 72 a, and 72 b is linearly formed andarranged in an axial center portion of each of the arm portions L,parallel to an extending direction of that arm portion L.

The detection electrodes 71 a, 71 b, 72 a, and 72 b have the sameconfiguration as those of the first drive electrodes 301 and the seconddrive electrodes 302. Each of the detection electrodes 71 a, 71 b, 72 a,and 72 b is constituted of a multilayer body of a lower electrode layer,a piezoelectric material layer, and an upper electrode layer andconverts mechanical deformation of each of the arm portions L to anelectrical signal. In other words, the detection electrodes 71 a, 71 b,72 a, and 72 b each have a function of detecting deformations of the armportions L in the Z-axis direction.

In this embodiment, one angular velocity detection axis is set in anaxis direction parallel to the X-axis and the other angular velocitydetection axis is set in an axis direction parallel to the Y-axis. Insuch a configuration, the detection electrodes 71 a, 71 b, 72 a, and 72b function as detectors for detecting an angular velocity around theX-axis and an angular velocity around the Y-axis.

To the drive electrodes 301 and 302, alternating-current voltages inopposite phases are applied. With this, the beams 11 a, 11 b, 12 a, and12 b and the pendulums 21 a, 21 b, 22 a, and 22 b of the frame 10vibrate in the vibration mode (basic vibration) shown in FIG. 3A. FIG.5A is a schematic perspective view for illustrating vibration states ofthe respective pendulums 21 a, 21 b, 22 a, and 22 b when an angularvelocity around the X-axis acts on the frame 10. On the other hand, FIG.5B is a schematic perspective view for illustrating vibration states ofthe respective pendulums 21 a, 21 b, 22 a, and 22 b when an angularvelocity around the Y-axis acts on the frame 10.

When an angular velocity around the X-axis acts on the frame 10vibrating in the basic vibration, as shown in FIG. 5A, in the respectivependulums 21 a, 21 b, 22 a, and 22 b, Coriolis forces F1 are generatedin directions orthogonal to vibration directions at that point of time.With this, one pair of the pendulums 21 a and 22 b adjacent to eachother in the X-axis direction are deformed to a positive direction ofthe Z-axis due to the Coriolis forces F1 and then the amounts ofdeformation are detected by the detection electrodes 71 a and 72 b.Further, the other pair of the pendulums 22 a and 21 b adjacent to eachother in the X-axis direction are deformed to a negative direction ofthe Z-axis due to the Coriolis forces F1 and then the amounts ofdeformation are detected by the detection electrodes 72 a and 71 b.

On the other hand, when an angular velocity around the Y-axis acts onthe frame 10 vibrating in the basic vibration, as shown in FIG. 5B, inthe respective pendulums 21 a, 21 b, 22 a, and 22 b, Coriolis forces F2are generated in directions orthogonal to vibration directions at thatpoint of time. With this, one pair of the pendulums 21 a and 22 aadjacent to each other in the Y-axis direction are deformed to anegative direction of the Z-axis due to the Coriolis forces F2 and thenthe amounts of deformation are detected by the detection electrodes 71 aand 72 a. Further, the other pair of the pendulums 21 b and 22 badjacent to each other in the Y-axis direction are deformed to apositive direction of the Z-axis due to the Coriolis forces F2 and thenthe amounts of deformation are detected by the detection electrodes 71 band 72 b.

Also in the case where an angular velocity is generated around an axisin a direction obliquely intersecting the X-axis or the Y-axis, theangular velocity is detected by the same principle as described above.In other words, the pendulums 21 a, 21 b, 22 a, and 22 b are deformeddue to Coriolis forces corresponding to an X-direction component and aY-direction component of the angular velocity and then, the amounts ofdeformation are detected by the detection electrodes 71 a, 71 b, 72 a,and 72 b. A drive circuit of the angular velocity sensor 1 detects,based on the outputs from those detection electrodes, an angularvelocity around the X-axis and an angular velocity around the Y-axis. Inthis manner, an angular velocity around an arbitrary axis parallel tothe XY-plane can be detected.

[Drive Circuit]

FIG. 6 is a block diagram showing a drive circuit 100 of the angularvelocity sensor 1. In FIG. 6, for the sake of convenience, the beams 11a, 11 b, 12 a, and 12 b of the frame 10 are linearly shown and further,illustration of the support mechanism 80 is omitted.

The drive circuit 100 includes a Go1 terminal, a Go2 terminal, a GFBterminal, and a Vref terminal. The Go1 terminal is connected to theupper electrode layers of the first drive electrodes 301. The Go2terminal is connected to the upper electrode layers of the second driveelectrodes 302. The GFB terminal is connected to the reference electrode60. The Vref terminal is connected to the lower electrode layers of thedrive electrodes 301 and 302 and to the lower electrode layers of thedetection electrodes 51 a, 51 b, 71 a, 71 b, 72 a, and 72 b.

The drive circuit 100 further includes a Gxy1 terminal, a Gxy2 terminal,a Gxy3 terminal, a Gxy4 terminal, a Gz1 terminal, and a Gz2 terminal,which are electrically connected to the respective detection electrodesof the angular velocity sensor 1. The Gxy1 terminal is connected to thedetection electrode 71 a of the pendulum 21 a and the Gxy2 terminal isconnected to the detection electrode 72 b of the pendulum 22 b. The Gxy3terminal is connected to the detection electrode 71 b of the pendulum 21b and the Gxy4 terminal is connected to the detection electrode 72 a ofthe pendulum 22 a. Further, the Gz1 terminal is connected to thedetection electrode 51 a of the frame 10 and the Gz2 terminal isconnected to the detection electrode 51 b of the frame 10.

In the drive circuit 100, the Go1 terminal is connected to an output endof a self-oscillating circuit 101. The self-oscillating circuit 101generates drive signals (alternating-current signals) for driving thedrive electrodes 301 and 302. The Go2 terminal is connected to theoutput end of the self-oscillating circuit 101 via an inverse amplifier102. The inverse amplifier 102 inverts the phases of the drive signalsgenerated in the self-oscillating circuit 101. With this, the firstdrive electrodes 301 and the second drive electrodes 302 are stretchedand contracted in opposite phase to each other. The Vref terminal isconnected to a predetermined reference potential. The referencepotential may be a ground potential or a constant offset potential.

The drive circuit 100 further includes an arithmetic circuit 103,detector circuits 104 x, 104 y, and 104 z, and smoothing circuits 105 x,105 y, and 105 z. The GFB terminal, the Gxy1 terminal, the Gxy2terminal, the Gxy3 terminal, the Gxy4 terminal, the Gz1 terminal, andthe Gz2 terminal are connected to an input end of the arithmetic circuit103.

The arithmetic circuit 103 generates, based on an output voltage of thereference electrode 60, which is supplied via the GFB terminal, areference signal and outputs the reference signal to theself-oscillating circuit 101. The arithmetic circuit 103 includes afirst differential circuit for generating an angular velocity signalaround the X-axis, a second differential circuit for generating anangular velocity signal around the Y-axis, and a third differentialcircuit for generating an angular velocity signal around the Z-axis. Anoutput of the detection electrode 71 a is denoted by xy1, an output ofthe detection electrode 72 b is denoted by xy2, an output of thedetection electrode 71 b is denoted by xy3, an output of the detectionelectrode 72 a is denoted by xy4, an output of the detection electrode51 a is denoted by z1, and an output of the detection electrode 51 b isdenoted by z2. At this time, the first differential circuit calculates(xy1+xy2)−(xy3+xy4) and outputs the calculated value to the detectorcircuit 104 x. The second differential circuit calculates(xy1+xy4)−(xy2+xy3) and outputs the calculated value to the detectorcircuit 104 y. Further, the third differential circuit calculates(z1−z2) and outputs the calculated value to the detector circuit 104 z.

The detector circuits 104 x, 104 y, and 104 z subject theabove-mentioned differential signals to full-wave rectification insynchronism with the drive signals from the self-oscillating circuit 101or the reference signal in order to obtain direct current signals. Thesmoothing circuits 105 x, 105 y, and 105 z smooth the outputs of thedetector circuits. A direct current voltage signal ωx output from thesmoothing circuit 105 x contains information on the magnitude anddirection of the angular velocity around the X-axis. Further, a directcurrent voltage signal ωy output from the smoothing circuit 105 ycontains information on the magnitude and direction of the angularvelocity around the Y-axis. In addition, a direct current voltage signalωz output from the smoothing circuit 105 z contains information on themagnitude and direction of the angular velocity around the Z-axis. Inother words, the magnitudes of the direct current voltage signals ωx,ωy, and ωz with respect to the reference voltage (Vref) correspond tothe information on the magnitudes of the angular velocities and thepolarities of the direct current voltages correspond to the informationon the directions of the angular velocities.

As described above, according to this embodiment, the angular velocitiesaround the axes of the X-axis direction, the Y-axis direction, and theZ-axis direction can be detected based on the respective deformations,in an XZ-plane, a YZ-plane, and the XY-plane, of the frame 10 vibratingin the XY-plane. With this, it becomes possible to detect, with highaccuracy, the angular velocities around the three axes of the X-axisdirection, the Y-axis direction, and the Z-axis direction withoutincreasing a thickness dimension. In addition, it becomes possible toachieve a reduction in thickness of the sensor.

Further, the angular velocity sensor according to this embodiment isincorporated in an electronic apparatus such as a digital still camera,a video camera, a virtual reality apparatus, or a car navigation systemand widely used as a sensor component for shake detection, operationdetection, direction detection, and the like. In particular, accordingto this embodiment, it is possible to achieve a reduction in size andthickness of the sensor, and hence it is also possible to sufficientlysatisfy demands for a reduction in size, thickness, and the like of theelectronic apparatus.

[Support Mechanism]

Next, the support mechanism 80 will be described.

The support mechanism 80 includes, as shown in FIG. 1, a base portion 81and a plurality of joint portions 82 a, 82 b, 82 c, and 82 d.

The base portion 81 is constituted of an annular frame body including aninner peripheral portion surrounding an outside of the frame 10. In thisembodiment, the base portion 81 is constituted of a square frame bodyhaving a longitudinal direction in the X-axis direction and a lateraldirection in the Y-axis direction. The joint portions 82 a to 82 d areformed between the frame 10 and the base portion 81. In other words, thejoint portions 82 a to 82 d join between the connections 13 a to 13 d ofthe frame 10 and the inner peripheral portion 81 a of the base portion81.

Each of the joint portions 82 a to 82 d is formed of a beam bent in theXY-plane and includes a first end portion w1, a second end portion w2, afirst bend portion wa, and a second bend portion wb.

The first end portion w1 linearly extends from each of the connections13 a to 13 d toward the connection portion opposed to it in the Y-axisdirection. The second end portions w2 are respectively connected to theinner peripheral portions 81 a and 81 b of the two sides of the baseportion 81, the two sides being parallel to the X-axis direction. In theexample shown in the drawing, the second end portions w2 of the jointportions 82 a and 82 b are connected to one inner peripheral portion 81a and the second end portions w2 of the joint portions 82 c and 82 d areconnected to the other inner peripheral portion 81 b.

Each of the first bend portions wa is positioned between the first endportion w1 and the second end portion w2 and is formed so as to be bentback by about 180 degrees from the first end portion w1 toward the baseportion 81. Each of the second bend portions wb is positioned betweenthe second end portion w2 and the first bend portion wa and is formed soas to be bent back by about 180 degrees from the second end portion w2toward the frame 10. An area between the first bend portion wa and thesecond bend portion wb is formed by appropriately bending itsubstantially along the inner peripheral portion of the base portion 81.

The extending direction of the first end portion w1 is not limited onlyto the Y-axis direction and may be the X-axis direction. By setting theextending direction of the first end portion w1 to the Y-axis directionor the X-axis direction, the shape of the angular velocity sensor 1 issymmetric with respect to the Y-axis direction or the X-axis direction,and hence it becomes easy to adjust the vibration properties of theframe 10. As a matter of course, it is not limited thereto, and a firstend portion extending in the Y-axis direction and a first end portionextending in the X-axis direction may be provided. It should be notedthat although the first end portion may be formed to extend obliquely tothe Y-axis direction or the X-axis direction, if the first end portionis formed along the Y-axis direction or the X-axis direction, it becomesadvantageous for a reduction in size of the elements.

By configuring the joint portions 82 a to 82 d as described above, itbecomes possible to achieve a reduction in size of the angular velocitysensor 1. FIG. 7 are plan views for comparing the size of the angularvelocity sensor 1 according to this embodiment with the size of anangular velocity sensor 2 according to another embodiment of the presentdisclosure. FIG. 7A shows the angular velocity sensor 1 and FIG. 7Bshows the angular velocity sensor 2.

The angular velocity sensor 2 shown for comparison includes a frame 110having a square shape and four joint portions 182 a, 182 b, 182 c, and182 d that fix the frame 110 to a fixing portion (not shown). The frame110 is constituted of, for example, a pair of first linear beams 111 aand 111 b and a pair of second linear beams 112 a and 112 b as in thefirst embodiment.

Here, a case where the outer shape of the frame 10 of the angularvelocity sensor 1 is set to a square S having a size corresponding tothe size of the frame 110 of the angular velocity sensor 2 will bediscussed. In the angular velocity sensor 2, the beams 111 a, 111 b, 112a, and 112 b are linearly formed and hence, for example, the jointportions 182 a to 182 d need to be formed in an outer area of the frame110, the outer area being denoted by L2. In contrast, in the angularvelocity sensor 1, due to the fact that each of the beams 11 a, 11 b, 12a, and 12 b is formed to have a bow shape and the first end portions w1of the joint portions 82 a to 82 d are linearly formed as describedabove, for example, the joint portions 82 a to 82 d can be formed withina range denoted by L1 smaller than L2.

In other words, the center portion of each beam of the frame projects tothe inside of the frame so as to have a bow shape and in contrast, therecess portion having a bow shape is formed on the outside of the centerportion of each beam. By arranging a part of each of the joint portionsin this recess portions, the joint portion can be compactly arranged.Thus, it becomes possible to reduce the size of the angular velocitysensor.

In the angular velocity sensor 1 according to this embodiment, the jointportions 82 a to 82 d are, as shown in FIG. 1, each provided with twobend portions wa and wb. With this, the elasticity of the joint portions82 a to 82 d is lowered and thus, following vibration of the frame 10,the joint portions 82 a to 82 d can be deformed. Thus, it is possible tosupport the frame 10 without prohibiting straining and deformation dueto the vibration mode of the frame 10 and the Coriolis forces. Suchaction can be similarly obtained also in the angular velocity sensor 2.

In the angular velocity sensor 1 according to this embodiment, as shownin FIG. 1, the bend portions wa and wb are arranged in the recessportions 11 t and 12 t on the outside of each beam of the frame 10. Withthis, in a gap between each of the four connections 13 a to 13 d of theframe 10 and the base portion 81, one beam of each of the joint portions82 a to 82 d is enabled to be arranged. It is possible to reduce thesize of the angular velocity sensor 1 and, at the same time, to ensuredriving/detecting properties because the elasticity of the jointportions 82 a to 82 d is maintained.

As described above, according to this embodiment, it is possible toachieve a reduction in size of the angular velocity sensor. Further,with the angular velocity sensor 1 according to this embodiment, it ispossible to reduce the size of a space between the beams 11 a, 11 b, 12a, and 12 b and the pendulums 21 a, 21 b, 22 a, and 22 b. Therefore, forexample, in the case where the frame 10 is formed of one siliconsubstrate by an etching technique, it is possible to reduce an area tobe removed by etching and to realize stable etching because coarse/finedistribution of an etching area becomes small. With this, it becomespossible to form the angular velocity sensor with high accuracy.

In addition, with the angular velocity sensor 1 according to thisembodiment, it is possible to prevent the detection sensibility of theangular velocity from being fluctuated due to external impact and tosubstantially reduce influence of disturbance such as vibration orimpact acting on the electronic apparatus, for example.

Next, referring to FIG. 1, in two sides of the base portion 81, whichare opposed to each other in the Y-axis direction, terminal arraysconsisting of a plurality of terminal portions 83 are arranged. In eachof those sides of the base portion 81, the terminal portions 83 arearranged in parallel in the X-axis direction. Each of the terminalportions 83 is electrically connected to a land on the wiring substrate(not shown).

The terminal arrays of the terminal portions 83 may be arranged in thetwo sides of the base portion 81, which are opposed to each other in theX-axis direction. Alternatively, in each side of the base portion 81, aterminal array as described above may be arranged.

The connection mode is not particularly limited and a flip chip methodor a wire bonding method may be employed as the connection mode. In thisembodiment, the flip chip method of electrically and mechanicallyconnecting the respective terminal portions 83 to the land on the wiringsubstrate is employed.

The plurality of terminal portions 83 are connected via wires (notshown) so as to individually correspond to the drive electrodes 301 and302, the detection electrodes 51 a, 51 b, 71 a, 71 b, 72 a, and 72 b,the reference electrode 60, another reference electrode, and the like onthe frame 10. Those wires are passed along a surface of the frame 10,surfaces of the arm portions L of the respective pendulums 21 a, 21 b,22 a, and 22 b, surfaces of the respective joint portions 82 a to 82 d,and a surface of the base portion 81.

In addition, between the inner peripheral portions 81 a and 81 b of thebase portion 81 and the terminal arrays of the terminal portions 83,grooves 84 a and 84 b are formed. Each of the grooves 84 a and 84 bextends through the base portion 81 in the Z-axis direction and isformed along the X-axis direction. Those grooves 84 a and 84 b areprovided for suppressing vibration between the base portion 81 and theframe 10, which are fixed on the wiring substrate via the respectiveterminal portions 83, from being transmitted. It should be noted thatformation of the grooves 84 a and 84 b may be omitted depending onneeds.

In the angular velocity sensor 1 having the above-mentionedconfiguration, it is possible to suppress transmission of disturbanceacting on the angular velocity sensor 1, for example, transmission ofexternal impact acting on the electronic apparatus via the wiringsubstrate to the angular velocity sensor 1, by using the grooves 84 aand 84 b. With this, it is possible to suppress the vibration propertiesof the angular velocity sensor 1 from being fluctuated and to maintain astable angular velocity detection property.

Further, formation of the grooves 84 a and 84 b also suppressestransmission of vibration from the frame 10 to the base portion 81, andhence it is possible to eliminate an adverse affect on other electroniccomponents on the wiring substrate.

FIG. 8 shows one result of experimentation in which two angular velocitysensors having different configurations are mounted on wiring substratesand the frames are subjected to the basic vibration in order to evaluatethe amount of vibration in each of predetermined points. Sample 1corresponds to the angular velocity sensor 1 shown in FIG. 7A and Sample2 corresponds to the angular velocity sensor shown in FIG. 7B.Measurement point A was set to one arbitrary pendulum of each of theangular velocity sensors and Measurement point B was set to an endportion on a base portion side of a joint portion connecting the frameand the base portion. Further, Measurement point C was set to anarbitrary point on the wiring substrate. As shown in FIG. 8, Sample 1can substantially reduce the amounts of vibration in Measurement pointsB and C in comparison with Sample 2.

In addition, in the case where the wiring substrate incorporating theangular velocity sensor 1 is reflow-mounted on a control substrate of anelectronic apparatus, it is possible to suppress thermal deformation ofthe wiring substrate due to a reflow temperature from influencing theframe 10. With this, it is possible to suppress the vibration propertiesof the frame 10 before and after reflow mounting from being fluctuated.

Second Embodiment

FIG. 9 is a plan view showing an entire configuration of an angularvelocity sensor according to a second embodiment of the presentdisclosure. In the following, configurations different from the firstembodiment will be mainly described, the same configurations as theabove-mentioned embodiment will be denoted by the same referencesymbols, and the description thereof will be omitted or simplified.

An angular velocity sensor 3 according to this embodiment includes agroove 85 a formed between the inner peripheral portion 81 a of the baseportion 81 and the terminal array of the terminal portions 83 and agroove 85 b formed between the inner peripheral portion 81 b of the baseportion 81 and the terminal array of the terminal portions 83. In thisembodiment, the grooves 85 a and 85 b extend through the base portion 81in the Z-axis direction and each include a first groove portion 851formed along the X-axis direction and second groove portions 852 formedin continuous with the first groove portion 851 along the Y-axisdirection. Those grooves 85 a and 85 b are provided for suppressingtransmission of vibration between the base portion 81 and the frame 10,which are fixed on the wiring substrate via the respective terminalportions 83.

In FIG. 9, the grooves 85 a and 85 b are symmetrically formed on thebase portion 81. In this embodiment, in the grooves 85 a and 85 b,distal ends of the groove portions 852 extending from both ends of onegroove portion 851 and distal ends of the groove portions 852 extendingfrom both ends of the other groove portion 851 are formed so as to beopposed to each other at center portions in two sides of the baseportion 81, the two sides being parallel to each other in the Y-axisdirection. With this, a portion between the frame 10 and an outerperipheral portion of the base portion 81 is, in substantially theentire periphery, separated by the grooves 85 a and 85 b. Gaps betweenthe one groove portions 852 and the other groove portions 852 that areopposed to each other form passages through which a plurality of wiringpatterns that connect between the plurality of terminal portions 83 anda plurality of electrodes on the frame 10 are passed.

According to this embodiment, the grooves 85 a and 85 b are formed so asto surround the substantially entire periphery of the frame 10, andhence it becomes possible to substantially reduce transmission ofvibration between the base portion 81 and the frame 10. With this, it ispossible to make the vibration properties of the frame 10 stable and toensure a highly accurate angular velocity detection property.

Third Embodiment

FIG. 10 is a plan view showing an entire configuration of an angularvelocity sensor according to a third embodiment of the presentdisclosure. In the following, configurations different from the firstembodiment will be mainly described, the same configurations as theabove-mentioned embodiment will be denoted by the same referencesymbols, and the description thereof will be omitted or simplified.

An angular velocity sensor 4 according to this embodiment includes jointportions 86 a, 86 b, 86 c, and 86 d that join between the frame 10 andthe base portion 81. Each of the joint portions 86 a to 86 d is formedof a beam bent in the XY-plane and includes a first end portion w1, asecond end portion w2, a first bend portion wa, and a second bendportion wb.

The first end portion w1 linearly extends from each of the connections13 a to 13 d toward the connection portion opposed to it in the Y-axisdirection. The second end portion w2 is connected to each of innerperipheral portions 81 c and 81 d in two sides of the base portion 81,the two sides being parallel to the Y-axis direction. In the exampleshown in the drawing, the second end portions w2 of the joint portions86 a and 86 d are integrated with each other and connected to one innerperipheral portion 81 d and the second end portions w2 of the jointportions 86 b and 86 c are integrated with each other and connected tothe other inner peripheral portion 81 d.

Each of the first bend portions wa is positioned between the first endportion w1 and the second end portion w2 and is formed so as to be bentback by about 180 degrees from the first end portion w1 toward the baseportion 81. Each of the second bend portions wb is positioned betweenthe second end portion w2 and the first bend portion wa and is formed soas to be bent back by about 180 degrees from the second end portion w2toward the frame 10. An area between the first bend portion wa and thesecond bend portion wb is formed by appropriately bending itsubstantially along the inner peripheral portion of the base portion 81.

In this embodiment, as shown in FIG. 10, the bend portions wa and wb arearranged in the recess portions 11 t and 12 t on the outside of therespective beams of the frame 10. Further, in a gap between each of thefour connections 13 a to 13 d of the frame 10 and the base portion 81,two beams of each of the joint portions 86 a to 86 d are arranged.

In addition, in this embodiment, in the inner peripheral portions 81 aand 81 b of the two sides of the base portion 81, projecting portions 87a and 87 b that project toward the frame 10 are formed, the two sidesbeing parallel in the X-axis direction. Those projecting portions 87 aand 87 b are opposed to an outer periphery of the second bend portionswb of the respective joint portions 86 a to 86 d via a predeterminedgap.

With the angular velocity sensor 4 according to this embodimentconfigured as described above, it is possible to obtain the same actionas that of the angular velocity sensor 3 according to the secondembodiment. Further, according to this embodiment, the length of thejoint portions 86 a to 86 d can be increased, and hence it is possibleto form the sensor in a compact size and to support the frame 10 withoutprohibiting straining and deformation due to the vibration mode of theframe 10 and the Coriolis forces.

As described above, although the embodiments of the present disclosureare described, it is needless to say that the present disclosure is notlimited only to the above-mentioned embodiments and variousmodifications can be made without departing from the gist of the presentdisclosure.

For example, as shown in FIG. 11, the connections 13 a to 13 d of theframe 10 may be provided with a plurality of weights 14 a, 14 b, 14 c,and 14 d corresponding to the pendulums 21 a, 21 b, 22 a, and 22 b. Theweights 14 a to 14 d function as counter weights of the pendulums 21 a,21 b, 22 a, and 22 b. With this, it becomes easy to adjust the vibrationproperties (resonance frequency, detuning, etc.) of each of thependulums 21 a, 21 b, 22 a, and 22 b.

Alternatively, as shown in FIG. 12, for example, bend portions wa1 andwb1 of a joint portion 82 d may be formed to be wider and those portionsmay be set to function as a counter weight as described above.

It should be noted that the present disclosure can be also configured asfollows.

In an embodiment, an angular velocity sensor is provided. The angularvelocity sensor includes

an annular frame including

a pair of first beams that extend in a first direction and are opposedto each other in a second direction orthogonal to the first direction,

a pair of second beams that extend in the second direction and areopposed to each other in the first direction, and

a plurality of connections configured to connect between the pair offirst beams and the pair of second beams;

a drive unit configured to vibrate the frame in a first plane, to whichthe first direction and the second direction belong, in a vibration modein which when one pair of the pair of first beams and the pair of secondbeams move closer to each other, the other pair move away from eachother, and when the one pair move away from each other, the other pairmove closer to each other;

a first detector configured to detect, based on the amount ofdeformation of the frame in the first plane, an angular velocity aroundan axis of a third direction orthogonal to the first plane, the framevibrating in the vibration mode; and

a support mechanism including

an annular base portion including an inner peripheral portionsurrounding an outside of the frame, and

a plurality of joint portions configured to join between the innerperipheral portion and the plurality of connections.

In the embodiment, each of the plurality of joint portions includes

a first end portion that is connected to one of the plurality ofconnections,

a second end portion that is connected to the inner peripheral portion,and

a structural portion that is provided between the first end portion andthe second end portion and includes at least a bend portion.

In an embodiment, the base portion includes

a terminal array including a plurality of terminal portions that arearranged along one of the first direction and the second direction, and

a groove formed along the terminal array between the terminal array andthe inner peripheral portion.

In an embodiment, the base portion is a square frame body including twosides opposed to each other in the first direction and two sides opposedto each other in the second direction, and

the groove includes

first groove portions that are formed in the two sides opposed to eachother in the first direction, and

second groove portions that are formed in the two sides opposed to eachother in the second direction and communicate with the first grooveportions.

In an embodiment, the pair of first beams includes a pair of first beamportions including first curved portions that form first recesses byprojecting to a direction in which the first curved portions are opposedto each other, and

the pair of second beams includes a pair of second beam portionsincluding second curved portions that form second recesses by projectingto a direction in which the second curved portions are opposed to eachother.

In an embodiment, at least a part of the plurality of joint portions ispositioned in one of the first recess and the second recess.

In an embodiment, first pendulums are provided in a pair of firstconnections in a diagonal relationship out of the plurality ofconnections and vibrate in synchronism with vibration of the frame inthe first plane;

second pendulums are provided in a pair of second connections in adiagonal relationship out of the plurality of connections and vibrate insynchronism with vibration of the frame in the first plane; and

a second detector is configured to detect angular velocities around axesof two predetermined directions in the first plane, based on the amountsof deformation of the first pendulums and the second pendulums in adirection orthogonal to the first plane.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. An angular velocity sensor,comprising: an annular frame including a pair of first beams that extendin a first direction and are opposed to each other in a second directionorthogonal to the first direction, a pair of second beams that extend inthe second direction and are opposed to each other in the firstdirection, and a plurality of connections configured to connect betweenthe pair of first beams and the pair of second beams; a drive unitconfigured to vibrate the frame in a first plane, to which the firstdirection and the second direction belong, in a vibration mode in whichwhen one pair of the pair of first beams and the pair of second beamsmove closer to each other, the other pair move away from each other, andwhen the one pair move away from each other, the other pair move closerto each other; a first detector configured to detect, based on theamount of deformation of the frame in the first plane, an angularvelocity around an axis of a third direction orthogonal to the firstplane, the frame vibrating in the vibration mode; and a supportmechanism including an annular base portion including an innerperipheral portion surrounding an outside of the frame, and a pluralityof joint portions configured to join between the inner peripheralportion and the plurality of connections.
 2. The angular velocity sensoraccording to claim 1, wherein each of the plurality of joint portionsincludes a first end portion that is connected to one of the pluralityof connections, a second end portion that is connected to the innerperipheral portion, and a structural portion that is provided betweenthe first end portion and the second end portion and includes at least abend portion.
 3. The angular velocity sensor according to claim 2,wherein the base portion includes a terminal array including a pluralityof terminal portions that are arranged along one of the first directionand the second direction, and a groove formed along the terminal arraybetween the terminal array and the inner peripheral portion.
 4. Theangular velocity sensor according to claim 3, wherein the base portionis a square frame body including two sides opposed to each other in thefirst direction and two sides opposed to each other in the seconddirection, and the groove includes first groove portions that are formedin the two sides opposed to each other in the first direction, andsecond groove portions that are formed in the two sides opposed to eachother in the second direction and communicate with the first grooveportions.
 5. The angular velocity sensor according to claim 1, whereinthe pair of first beams includes a pair of first beam portions includingfirst curved portions that form first recesses by projecting to adirection in which the first curved portions are opposed to each other,and the pair of second beams includes a pair of second beam portionsincluding second curved portions that form second recesses by projectingto a direction in which the second curved portions are opposed to eachother.
 6. The angular velocity sensor according to claim 5, wherein atleast a part of the plurality of joint portions is positioned in one ofthe first recess and the second recess.
 7. The angular velocity sensoraccording to claim 1, further comprising: first pendulums that areprovided in a pair of first connections in a diagonal relationship outof the plurality of connections and vibrate in synchronism withvibration of the frame in the first plane; second pendulums that areprovided in a pair of second connections in a diagonal relationship outof the plurality of connections and vibrate in synchronism withvibration of the frame in the first plane; and a second detectorconfigured to detect angular velocities around axes of two predetermineddirections in the first plane, based on the amounts of deformation ofthe first pendulums and the second pendulums in a direction orthogonalto the first plane.